The fertilizing capacity of golden hamster epididymal spermatozoa in relation to age, number, motility and morphology.

Experiments with spermatozoa of prepubertal hamsters aged 35-48 days were performed in order to determine if the appearance of spermatozoa with fertilizing capacity in the cauda epididymis during puberty is related to changes in their morphology, motility and number. Epididymal spermatozoa of prepubertal animals were evaluated for number, motility and morphology and were injected into one uterine horn of a female, following induction of ovulation. A comparable number of sperm from mature animals (which served as control) was injected into the contralateral horn. Prior to 40 days fertilizing capacity was nil. It increased thereafter and reached control levels of 74% at 48 day age. Concomitantly there was an increase in the number of sperm per cauda epididymidis from less than 1 million to 55 million. Following removal of spermatozoa from the cauda the motility increased from 24% motile cells at the age of 39 days to 66% at the age of 48 days when most cells exhibited progressive motility. The percentage of cells having normal morphology increased from 18% at the age of 39 days to 50% at the age of 48 days. Developmental processes resulting in improvement of cell motility, morphology and number are correlated with attainment of fertilizing capacity. These processes seem to be gradual and occur between time of completion of spermatogenesis and time when capacity for fertilization is achieved.